Basic Scripting Concepts Flashcards

What does the `-z` test operator check in `[ -z "$var" ]`?

Answer: Whether $var is an empty string

`-z` returns true when the string has a length of zero.

Which command substitution syntax is POSIX-compatible and preferred in modern scripts?

Answer: $(command)

`$(command)` is the modern, nestable form of command substitution recommended by POSIX.

What value does `$#` represent in a shell script?

Answer: The number of positional parameters passed

`$#` expands to the count of positional parameters supplied when the script was invoked.

How do you make a script file executable so it can be run as `./myscript.sh`?

Answer: chmod +x myscript.sh

`chmod +x` adds the execute permission bit, allowing the file to be run directly.

In bash, what is the correct way to compare two integer variables `a` and `b` for equality inside `[ ]`?

Answer: [ $a -eq $b ]

`-eq` is the arithmetic equality operator used inside `[ ]` for numeric comparisons.

Which construct runs a block of commands repeatedly as long as a condition is TRUE?

Answer: while loop

A `while` loop evaluates its condition before each iteration and continues as long as it is true.

What happens if you use `local` to declare a variable inside a bash function?

Answer: The variable is only visible within the function

`local` restricts the variable's scope to the function and its children, preventing pollution of the global namespace.